Preparation of alkyl silanes

ABSTRACT

Olefins and metal aluminum tetraalkyls react with alkylhalosilanes to yield mixtures of tetraalkyl silanes which may be employed as functional fluids. For example, decene-1 and sodium aluminum tetraoctyl, NaAl(C 8  H 17 ) 4 , react with dialkyldichlorosilane. The mole ratio of sodium aluminum tetraalkyl to halosilane in from about 0.5:1.0 to about 1:1, and the ratio of olefin to the metal aluminate is selected to confer in the product mixture, the desired concentration of alkyl radicals derived from the olefin.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PATENTS

This application is a continuation-in-part of application Ser. No.198,514, filed May 24, 1988, now U.S. Pat. No. 4,916,245, and ofapplication Ser. No. 129,001, filed Dec. 3, 1987, now U.S. Pat. No.4,845,260, which in turn is a continuation-in-part of application Ser.No. 17,852, filed Feb. 24, 1987, now U.S. Pat. No. 4,711,965. Thisapplication is related to U.S. Pat. No. 4,711,966, which issued in myname on Dec. 8, 1987.

FIELD OF THE INVENTION

This invention relates to the reaction of olefins and alkali metalaluminum tetraalkyls (also known as alkali metal aluminates) with alkylhalosilanes. This invention is particularly directed to preparation oftetraalkylsilane mixtures produced by this reaction. Such mixtures areuseful as functional fluids.

BACKGROUND OF THE INVENTION

Methods for the synthesis of tetraalkyl silanes include the reaction ofalkyl magnesium halides or alkyl lithiums with halosilicon compounds;Tamborski et al U.S. Pat. No. 4,367,343, and Tamborski et al, "Synthesisand Properties of Silahydrocarbons, A Class of Thermally Stable, WideLiquid Range Fluids", Ind. Eno. Chem. Prod. Res. Dev. 22, 172-178(1983).

British patent 825,987 to Kali-Chemie AG discloses the reaction oftrialkyl aluminums with alkyl- or aryl- chlorosilanes.

Jenkner, British patent 900,132, (also to Kali-Chemie) pertains to thereaction of sodium aluminum tetraethyl with halosilanes, such as silicontetrachloride, with the reactants in a ratio of 4 to 1.

Bakshi et al, U.S. Pat. No. 4,595,777 pertains to the process ofreacting an alkylchlorosilane with a trialkylaluminum.

Giraitis et al, U.S. Pat. No. 3,398,171, relates to the reaction oforganosilanes and mixed metal compounds ANR_(n) Wherein A is an alkalimetal and M can be aluminum. The process is conducted at a reactiontemperature of -20° C. to +50° C. and uses a higher mole ratio ofreactants than utilized in this invention (compare the paragraphbridging Columns 5 and 6 of the reference patent with the description ofthis invention given below).

SUMMARY OF THE INVENTION

This invention pertains to the preparation of tetraalkylsilanes, whereinone or two alkyl groups are comparatively small and the other two orthree are comparatively large. The small alkyl groups preferably havefrom one to about four carbon atoms, while the larger groups preferablyhave from about 8 to about 14 carbon atoms each. These products areprepared by a process which comprises reacting an alkali metal aluminumtetraalkyl, MAlR'₄, and an olefin corresponding to R', with an alkylhalosilane, RSiX₃ or R_(2SiX) ₂. In the above formulas, each X is ahalide radical, R is the smaller alkyl group (preferably one to aboutfour carbons), and R' is the larger alkyl group. The process isconducted such that about 2 to about 4 moles of metal tetraalkyl arereacted with each 4 mole portion of alkyl halosilane employed.

More particularly, in the process of this invention one equivalent ofMAlR'₄ reactant combines with one equivalent of alkylhalosilanereactant. In order to assist the reaction through the effect of massaction, an excess of up to about one additional equivalent of R' radicalas MAlR'₄ can be utilized in the reaction mixture. For the process ofthis invention, one does not use a very large excess of MAlR'₄ reactant,since such excesses can cause the reaction to take a different course,which for the purpose of this invention is not desired; confer, Jenkner,and Giraitis et al, supra.

As indicated above, an olefin reactant corresponding to R', is used inthe process of this invention, in order to provide a portion of thelarger alkyl radicals in the product produced.

In a highly preferred embodiment, the alkyl radical R' corresponding tothe olefin differs from any of the alkyl radicals in the alkali metalaluminum tetraalkyl. By use of this preferred embodiment, a productmixture can be obtained which contains alkyl groups from the aluminumcompound, as well as a dissimilar alkyl group produced from the olefin.Product mixtures produced in this way can have a composition selected tohave one or more desired properties. In other words, the productcomposition can be `tailor-made` by selecting (a) the type andconcentration of the alkyl groups within the aluminum tetraalkyl, and(b) the olefin reactant.

Although the mechanism of the process of this invention is not known indetail, it is believed that the olefin reactant does not react directlywith the alkyl halosilane. More particularly, it appears that the olefinfirst forms an unidentified reaction intermediate containing aluminum,which reacts with the alkyl halosilane.

In my prior patent U.S. Pat. No. 4,711,965, cited above, I described areaction in which a mixture of sodium aluminum tetraalkyls is reactedwith an alkyl halosilane to produce a mixture of tetrahydrocarbylsilaneproducts. In the process of the invention described in this application,it is not necessary to use a mixture of sodium aluminum tetraalkyls inorder to prepare a mixed tetrahydrocarbylsilane product. Instead, onemay use just one sodium aluminum tetraalkyl, and employ an olefin inplace of the second aluminum tetraalkyl. The ability to replace onealkali metal aluminum tetraalkyl with an olefin in the process of myprior patent is entirely unexpected.

The process of this invention is simple, and has decided advantages. Forexample, with the process of the instant invention, it is unnecessary tomake a second aluminum tetraalkyl compound. Secondly, storage of metalaluminum tetraalkyl reactants is simplified, since only one aluminumtetraalkyl needs to be stored for subsequent reaction, rather than two.Furthermore, with the process of this invention, a whole family ofdifferent products can be made from one alkali metal aluminumtetraalkyl. More specifically, a family of products can be made byreacting the selected tetraalkyl with different, selected olefins.

Although a preferred embodiment of this invention comprises the reactionof an alkyl halosilane with one alkali metal aluminum tetraalkyl and oneolefin, it is to be understood that this invention comprises processesin which more than one metal aluminate and/or olefin are employed asreactants.

Products of this invention are useful as functional fluids, with suchdiverse suggested uses as engine lubrication, electrical insulation, andas heat transfer media. They can also be used as hydraulic fluids. Theproducts of this invention are particularly useful under hightemperature conditions where petroleum-based or synthetichydrocarbon-based fluids cannot meet specifications. Product mixturescan be made to achieve desired rheological properties.

DESCRIPTION OF PREFERRED EMBODIMENTS

In a highly preferred embodiment, this invention comprises a process forthe preparation of a mixture of tetraalkylsilanes having the formulaRSiR'₃ or R₂ SiR'₂ wherein R and R' are alkyl radicals, the radicalsdepicted by R' are alike or different, R has from 1 to about 4 carbonatoms, and R' has from about 8 to about 14 carbon atoms; said processcomprising contacting reactants (a), (b) and (c) at a reactiontemperature, wherein:

reactant (a) is an alkali metal aluminum tetraalkyl having the formulaMAlR'₄ wherein M is an alkali metal selected from the class consistingof lithium, sodium, and potassium, and R' has the same significance asabove,

reactant (b) is an alkylhalosilane silane having the formula RSiX₃ or R₂SiX₂, wherein each X is a halogen radical selected from fluoride,chloride, and bromide, and R has the same significance as above, and

reactant (c) is an olefin to which an alkyl radical R' corresponds,wherein R' has the same significance as above,

such that the mole ratio of reactant (a) to reactant (b) is from about0.5:1.0 to about 1:1, and the ratio of reactant (c) to reactant (a) isselected to confer in said product mixture of tetraalkylsilanes, thedesired concentration of radicals R' derived from said olefin.

As stated above, the process of this invention comprises a reaction ofan alkali metal aluminate, MAlR'₄. Lithium, sodium and potassiumaluminates can be used, with the lithium and sodium compounds beingpreferred. The sodium aluminates are highly preferred for reasons ofeconomics and availability. Preferably, each radical indicated by R' inthe formula MAlR'₄ is a hydrocarbyl, straight chain alkyl radical ofabout 8 to about 14 carbon atoms; however, it is to be understood thatthe radicals need not be limited to this structural configuration, andthe size of the radicals can be larger or smaller than those within thepreferred range.

The radicals of the preferred configuration and size appear to yield themore useful products, and they are preferred for that reason. However,any metal aluminate MAlR'₄ can be used for the process of thisinvention, so long as the radicals depicted by R' are stable under thereaction conditions employed, do not form an untoward amount ofundesirable co-product when subjected to the reaction conditionsemployed, or unduly retard the reaction because of steric hindrance.

As mentioned above, the metal aluminate reactant may contain one or moregroups indicated by R'. Alternatively, a mixture of metal aluminates canbe used. The metal aluminate or aluminates need not be pure; forexample, an aluminate can be used in the reaction mixture in which it isformed. Thus for example, Na, Al, and H₂ can be reacted in a hydrocarbonto form NaAlH₄, and the NaAlH₄, unisolated or isolated, can be reactedwith an olefin, such as octene-1, or a mixture of olefins, such asoctene-1 and decene-1 in a mole ratio of 2 to 1, and the resultantreaction mixture used as a reactant in the process of this invention.When the reactant is formed in this way, the olefin is generally used inexcess. Consequently, the metal aluminate reactant used in the instantprocess can frequently be admixed with an olefin, or mixture of olefinsfrom which the metal aluminate is prepared. Accordingly, the number ofmoles of olefin available for reaction in the metal aluminate reactantis the sum of moles of olefin in the metal aluminate plus moles ofunreacted olefin admixed with the metal aluminate.

The metal aluminate reactant can be formed in situ by (a) reacting analkali metal with aluminum, hydrogen and olefin in the presence of anorganoaluminum catalyst, and (b) adding additional catalyst to thereaction mixture during the reaction to insure formation of the metalaluminate reactant, MAlR'₄. Use of such procedures is illustrated in myprior copending application Ser. No. 129,001, filed Dec. 3, 1987, alldisclosure of which is incorporated herein by reference.

An olefin is intentionally added as a reactant to the reaction mixtureemployed in the process of this invention. In a highly preferredembodiment, the olefin(s) added are different from the olefin(s)employed to make the metal aluminate. The amount of olefin added as areactant is selected to confer in the product mixture, the desiredconcentration of R' radicals derived from the olefin. For example, onemay use a mixture of 1.5 moles of olefin and 0.75 mole of sodiumaluminum tetraalkyl reactant. When this mole ratio is employed, the moleratio of alkyl groups in the mixture of hydrocarbylsilanes produced willhave the ratio of 2:1. In other words, there will be twice as many molesof R' radicals conferred by the metal aluminate reactant as contributedby the olefin. In general, one may use a mole ratio of olefin to metalaluminate reactant within the range of 2:1 to 20:1. Greater or lesseramounts may be used, if desired for there is no real upper or lowerlimit to the amount of olefin which can be employed. However, a largeexcess of olefin reactant may not be feasible since it takes up aconsiderable portion of the reactor space. If a product distribution isdesired which requires an undesirable amount of olefin reactant, myprocess disclosed in U.S. Pat. No. 4,711,965, is preferred.

Thus, the process of this invention can be considered to have asignificant, advantageous relationship with the process of U.S. Pat. No.4,711,965, infra. As discussed above, in some instances the process ofthe instant invention is advantageous since it obviates the need toemploy a mixture of alkali metal aluminate reactants. On the other hand,in some instances the process of my prior patent is advantageous, sinceit obviates the need to employ an undesirably large amount of olefinreactant.

Of course, instead of using two metal aluminates and the process of myaforementioned patent, one may employ the process of this inventionusing a different olefin/metal aluminate mixture, and thereby eliminatethe need for a large amount of olefin reactant. For example, instead ofusing sodium aluminum tetraoctyl and an undesirably large amount ofdecene-1, one may use the process of this invention and `switch` thereactants, i.e. react sodium aluminum tetradecyl and octene-1 (with thealkyl halosilane). By changing the reactants in this way, a largerelative amount of olefin can be eliminated.

The process described herein can be used to make product mixtures whichare the same as or related to the product mixtures produced by themethods disclosed in U.S. Pat. No. 4,711,965, and 4,711,966. Examples ofolefins which can be employed in the process of this invention arementioned in the paragraph below.

Most olefins available in large commercial quantities are made fromnatural products or by chain growth of ethylene. In either case, theolefin usually has an even number of carbon atoms. However, it is to beunderstood that an even number of carbon atoms is not critical, and theolefin and MAlR'₄ reactants can correspond to or have R' radicals withan odd number of carbon atoms. Nevertheless, because of the more readyavailability of even numbered olefins, the preferred MAlR'₄ reactantsfor this invention have alkyl radicals (depicted by R') that are derivedfrom one or more of the following olefins:

octene-1

decene-1

dodecene-1

tetradecene-1

hexadecene-1

Such olefins are also preferred reactants for this invention.

The other reactant employed in the process of this invention is an alkyltrihalosilane, RSiX₃. In this reactant, R is a lower alkyl radical suchas methyl, ethyl, propyl, butyl, isopropyl, sec-butyl or the like.Preferably, R is unbranched. More preferably, R is methyl. The threegroups indicated by X are halide radicals; preferably all three are thesame; however, reactants with two or three halo groups per molecule canbe used. Reactants with two halo groups per molecule have the formulaR_(2SiX) ₂. In these reactants, R is a lower alkyl radical such asmethyl, ethyl, propyl, butyl, isopropyl, sec-butyl or the like.Preferably, R is unbranched. More preferably, R is methyl. Preferably,the halide groups are chloro or bromo radicals, most preferably they areall chloro groups. Although alkyl halosilanes in which the alkyl grouphas from 1 to 4 carbon atoms are preferred, it is to be understood thatone may use as a reactant a compound having the formula R''SiX₃ or R''₂SiX₂ wherein R''is an alkyl group that has 5 or more carbon atoms.

The process of this invention is conducted using a reaction temperaturethat is high enough to cause the reaction to take place at a reasonablerate, but not so high that it causes an undesirable amount of sidereaction or decomposition to occur. Generally speaking, a temperatureabove 150° C. and below 230° C. is used. Preferably, the temperature isfrom about 180° C. to 230° C.

The reaction time is not a truly independent variable but depends atleast to some extent on the other reaction conditions employed such asthe reaction temperature. Generally speaking, reaction is essentiallycomplete in from about 3 to 10 hours with 5 to 6 hours being typical.

The reaction pressure does not have a large effect on the course of thereaction. Atmospheric, sub-atmospheric and super atmospheric pressurecan be used. Atmospheric pressure or the autogenous pressure of thesystem is preferred.

Although the process of this invention is preferably conducted usingalkali metal aluminates, MAlR'₄, such as described above, it is to beborne in mind that similar reactants can also be used in this inventionin substantially the same way, to produce substantially the sameresults. Thus for example, one may use alkaline earth aluminates,M'(AlR'₄)₂, wherein M' is Mg, Ca or Ba. When these materials are used inthe process of this invention, one-half of the molar quantitiesdescribed above for MAlR'₄ reactants are employed, since each moleculeof the alkaline earth compounds contains two, i.e. twice as many,(AlR'₄) groups.

EXAMPLE 1

To a 1 liter autoclave was charged 172.4 grams of a sodium aluminumtetradecyl NaAl(C₁₀ H₂₁)₄ solution consisting essentially of 167.2millimoles of sodium aluminum tetradecyl and 334 5 millimoles of decene.The total number of moles of C₁₀ alkyl groups available for bonding wasequal to [(4×167.2)+334.5] or 1003.3 millimoles. There was also charged74.98 grams of octene-1 (668.9 millimoles). The mole fraction ofoctene-1 was equal to 0.40.

The autoclave was also charged with 29.4 grams of methyl trichlorosilane(196.7 millimoles).

The reaction mixture was heated at 190° C. for 5 hours. It was thencooled, and hydrolyzed by slow addition to 750 milliliters of 15 percentcaustic solution. The hydrolysis was conducted using rapid agitation.After hydrolysis, the organic phase was washed with caustic, and thenseveral times with water.

The organic phase was stripped under vacuum to remove excess olefinreactant and vinylidene olefin produced as a by-product. There wasobtained a 94 percent yield of a silahydrocarbon mixture having thefollowing composition:

    ______________________________________                                                                     Calculated                                       Component       Mole Fraction                                                                              Mole Fraction                                    ______________________________________                                        1.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.3                                                           0.069        0.064                                        2.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.2 (C.sub.10 H.sub.21)                                       0.281        0.288                                        3.  CH.sub.3 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21).sub.2                                        0.420        0.432                                        4.  CH.sub.3 Si(C.sub.10 H.sub.21).sub.3                                                          0.230        0.216                                        ______________________________________                                    

The calculated mole fraction set forth above is derived from therelationship (a+b)³, i.e.:

    a.sup.3 +3a.sup.2 b+3ab.sup.2 +b.sup.3

wherein a is the mole fraction of one alkyl component, and b is the molefraction of the other alkyl component. The mole fraction of onecomponent is equal to the number of moles of that component divided bythe sum of the number of moles of both alkyl components available forbonding. As indicated above, the number moles of alkyl component in onecase is equal to the number of moles of alkyl groups present in thesodium tetraalkyl aluminate reactant, plus the number of moles of excessolefin admixed with that reactant. For the other component, the numberof moles of alkyl groups available for bonding is equal to the number ofmoles of olefin employed as reactant (c).

EXAMPLE 2

A 160 gram portion of metal aluminate solution used in the precedingexample was stripped at a temperature below 75° C. and at a pressure of3 mm Hg. The stripped solution contained 94.7 grams of NaAl(C₁₀ H₂₁)₄and 10.9 grams of decene-1. This mixture was charged to a 1 literreactor with 156.4 grams of octene-1, 40 grams of heptane, and 27.3grams of methyl trichlorosilane (182 millimoles).

The total C₁₀ alkyl available was 699 millimoles, and the total C₈ alkylavailable was 1396.4 millimoles. The mole fraction of C₈ alkyl was0.666.

The reaction mixture was heated and then worked up as in Example 1. Gaschromatographic analysis indicated that a 91.5 percent yield of amixture of products was obtained. The product mixture was as follows:

    ______________________________________                                                                     Calculated                                       Component       Mole Fraction                                                                              Mole Fraction                                    ______________________________________                                        1.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.3                                                           0.22         0.30                                         2.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.2 (C.sub.10 H.sub.21)                                       0.41         0.44                                         3.  CH.sub.3 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21).sub.2                                        0.28         0.22                                         4.  CH.sub.3 Si(C.sub.10 H.sub.21).sub.3                                                          0.09         0.04                                         ______________________________________                                    

The process of this example can be extended to the use of lithium andpotassium aluminum tetraalkyls in which the alkyl groups are octyl,decyl, dodecyl or tetradecyl. Such substances may be reacted withmethyl, ethyl, n-propyl, isopropyl, or n-butyl trichlorosilane or thetrifluoro or tribromo analogs of these substances in the presence of anolefin selected from octene-1, decene-1, dodecene-1, and tetradecene-1.The reaction can be conducted at exogenous pressure or at pressures ofup to 500 psi or higher. Such elevated pressures may be imposed by useof an inert gas atmosphere, e.g. nitrogen or argon. The reactions can beconducted at 180° C. to 230° C. for 3 to 10 hours. The mole ratio ofmetal aluminate to trihalosilane may be in the range of about (0.75:1.0)to (1.0:1.0). The mole ratio of added olefin (i.e. the olefin added as areactant and not including any olefin present with the sodium tetraalkylaluminate) can be in the range of from (1:2) to (1:20).

EXAMPLE 3

To a 1 liter autoclave was charged 163 grams of a solution containing214.3 millimoles of sodium tetraoctyl aluminate, NaAl(C₈ H₁₇)₄, and 495millimoles of octene-1. The autoclave was also charged with 113.5 gramsof decene-1 (811 millimoles) and 37.7 grams of methyl trichlorosilane.

The total C₈ alkyl available was equal to [(4×214.3)+495], and the molefraction of C₈ alkyl was 0.625.

Reaction and workup, as in the previous examples, result ed in an 84.1percent yield of product having the following composition:

    ______________________________________                                                                     Calculated                                       Component       Mole Fraction                                                                              Mole Fraction                                    ______________________________________                                        1.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.3                                                           0.40         0.24                                         2.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.2 (C.sub.10 H.sub.21)                                       0.41         0.44                                         3.  CH.sub.3 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21).sub.2                                        0.17         0.26                                         4.  CH.sub.3 Si(C.sub.10 H.sub.21).sub.3                                                          0.03         0.05                                         ______________________________________                                    

The sodium aluminum tetraoctyl in this and the following example wasprepared using tri-n-octylaluminum as a catalyst, while the aluminateused in Examples 1 and 2 was prepared using lithium aluminum hydride asa catalyst. It will be noted that the mole fractions found in Examples 1and 2 more closely conform to the calculated mole fractions than themole fractions in Examples 3 and 4. The reason for the disparity inactivity between the two types of metal aluminates is unknown. Thedisparity in activity is also unexpected.

With regard to the preparation of the tetraalkyl aluminate reactant, itis known in the art that lithium aluminum hydride reacts with olefins atabout 110°-120° C. forming complexes with the structure LiAlR₄. Sodiumaluminum hydride is not added to olefins even at 180° C. without thepresence of catalytic amounts of a material selected from trialkylaluminums, dialkyl aluminum hydrides, lithium aluminum hydride, oraluminum, zinc or lithium halide. The first three hydrogens are readilyreplaced at 80°-130° C., but the fourth requires a temperature of170°-230° C. or thereabouts, for about 3 to 6 hours. The process ispreferentially conducted in the presence of an excess of olefin, e.g. a1:8 mole ratio of NaAlH₄ to olefin, and 5-15 mole % (based on NaAlH₄) ofthe catalyst. A paraffin diluent can be used in the reaction mixture.

As an illustration of the preparation of NaAlR'₄, a reactor is chargedwith NaAlH₄, catalyst, and olefin, and heated for 1-2 hours at 125° C.,followed by 3-4 hours at 175° C. (It is believed the duration of theheating cycle can be reduced somewhat.) The product is discharged aftercooling. The final product typically contains 30-65% of NaAlR₄, and issuitable for most reactions. It is not necessary that the aluminate beemployed in the product mix; if desired it can be isolated from some orall of the other substances present in the resultant reaction mixture.

EXAMPLE 4

To a 1 liter autoclave was charged 290.8 grams of an octene-1 solutioncontaining 382 millimoles sodium aluminum tetraoctyl. The total C₈ alkylavailable from the metal aluminate and the octene-1 solvent was 2,412millimoles. There was also added to the autoclave 169 grams of decene-1,i.e. 1,206 millimoles. The mole fraction of C₈ alkyl was 0.666. Methyltrichlorosilane, 67.2 grams (450 millimoles) was also charged to thereaction vessel.

Reaction and workup, as before, resulted in an 89.8 percent yield of aproduct which was shown to have the following composition:

    ______________________________________                                                                     Calculated                                       Component       Mole Fraction                                                                              Mole Fraction                                    ______________________________________                                        1.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.3                                                           0.40         0.30                                         2.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.2 (C.sub.10 H.sub.21)                                       0.43         0.44                                         3.  CH.sub.3 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21).sub.2                                        0.15         0.22                                         4.  CH.sub.3 Si(C.sub.10 H.sub.21).sub.3                                                          0.02         0.04                                         ______________________________________                                    

EXAMPLE 5

In this example, a solution of sodium aluminum tetraoctyl prepared usinglithium aluminum hydride as a catalyst was employed. The total solutionwas 131 grams. Each milliliter contained 1.3036 millimoles of sodiumaluminum tetraoctyl and 3.085 millimoles of octene-1. The total C₈ alkylavailable was equal to [4×1.3036)+3.085]×131, or 1,087.2 millimoles.

The reaction vessel was also charged with 76.1 grams (543.7 millimoles)of decene-1 and 30 grams (200.9 millimoles) of methyl trichlorosilane.

The mole fraction of C₈ alkyl available was 0.667.

Reaction and workup, as before, resulted in a 92.1 percent yield ofproduct which, as in the previous examples, was shown by gaschromatography to have the following distribution:

    ______________________________________                                                                     Calculated                                       Component       Mole Fraction                                                                              Mole Fraction                                    ______________________________________                                        1.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.3                                                           0.36         0.30                                         2.  CH.sub.3 Si(C.sub.8 H.sub.17).sub.2 (C.sub.10 H.sub.21)                                       0.42         0.44                                         3.  CH.sub.3 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21).sub.2                                        0.19         0.22                                         4.  CH.sub.3 Si(C.sub.10 H.sub.21).sub.3                                                          0.03         0.04                                         ______________________________________                                    

EXAMPLE 6

To a 1 liter autoclave was charged 170.8 grams of a solution ofNaAl(n-octyl)₄ in octene-1/heptane, assaying 3.32% aluminum. (Thereforetotal aluminate was 210 millimoles. Total C₈ present was 1231millimoles: 840 millimoles bound on aluminum plus 391 millimoles presentas free olefin.)

Also charged to the autoclave were 616 millimoles of decene-1 (giving aratio C₈ /C₁₀ of 2/1); 323 millimoles of (CH₃)₂ SiCl₂ (giving a ratioAl/Si of 0.65/1); and 100 milliliters of n-heptane.

This reaction mixture was heated at 190° C. for 6 hours, after which thevessel was cooled. The liquid phase was decanted from the solid NaAlCl₄phase and hydrolyzed by addition to 1 liter of vigorously agitated 15%NaOH. The organic phase was separated, washed with 500 millimoles of 15%NaOH and then with successive portions of water until the washings wereneutral to litmus. After drying over MgSO₄, residual light olefins wereremoved under vacuum, yielding 79.3 grams of water-white product whichwas analyzed by GLC.

Purity was determined by GLC to be 94.35%, the remainder being C₁₈ andC₂₀ olefins. The overall yield was 76.7%. The composition of the productwas as follows:

    ______________________________________                                                                     Calculated                                       Component        Mole Fraction                                                                             Mole Fraction                                    ______________________________________                                        1.  (CH.sub.3).sub.2 Si(C.sub.8 H.sub.17).sub.2                                                    0.488       0.44                                         2.  (CH.sub.3).sub.2 Si(C.sub.8 H.sub.17)(C.sub.10 H.sub.21)                                       0.388       0.44                                         3.  (CH.sub.3).sub.2 Si(C.sub.10 H.sub.21).sub.2                                                   0.124       0.11                                         ______________________________________                                    

EXAMPLE 7

An aluminate was prepared from NaAlH₄ and a 2/1 (mole ratio) mixture of1-octene and 1-decene in 100% excess. A portion of this solution,containing 470.9 millimoles of aluminate, was reacted with 780millimoles of (CH₃)₂ SiCl₂ in an autoclave, heating with vigorousstirring at 190° C. for five hours.

After cooling, the organic phase was decanted from the solid NaAlCl₄phase and discharged into one liter of vigorously stirred 15% causticsolution. It was washed once with caustic solution and several timeswith water, then dried over MgSO₄. Low boiling components of the productmixture were removed under vacuum leaving 179.5 g of the desiredmaterial as bottoms.

GLC analysis of the dried solution showed a 4/4/1 (mole ratio) mixtureof the following:

(CH₃)₂ Si(C₈ H₁₇)₂,

(CH₃)₂ Si(C₈ H₁₇)(C₁₀ H₂₁), and

(CH₃)₂ Si(C₁₀ H₂₁)₂.

The yield based on (CH₃)₂ SiCl₂ was 77.6%. The product melted at -45° C.The viscosity at 40° C. was 4.77 centistokes, and the viscosity at 100°C. was 1.70 centistokes.

Products of this invention are useful as functional fluids, e.g.hydraulic fluids for military or other applications. Hydraulic fluidsare used in hydraulic systems to transmit pressure or energy. They alsoserve to reduce friction in bearings and between sliding surfaces inpumps and similar articles. Hydraulic and other functional fluids alsoprotect surfaces from rusting, and can remove undesirable particulatematter away from surfaces.

Like other functional fluid base stocks, the silahydrocarbons producedby the process of this invention can be admixed with additives such asrust inhibitors, antiwear agents, corrosion inhibitors and the like.

It is to be understood that modification of the above describedinvention can be made without departing from the spirit and scope of thefollowing claims.

I claim:
 1. A process for the preparation of a mixture oftetraalkylsilanes, said process comprising contacting reactants (a),(b), and (c) at a reaction temperature, wherein:reactant (a) is analkali metal aluminum tetraalkyl having the formula MAlR'₄ wherein M isan alkali metal selected from the class consisting of lithium, sodium,and potassium, R' is an alkyl radical having from about 8 to about 14carbon atoms, and the radicals depicted by R' are alike or different:reactant (b) is an alkylhalosilane having two halo groups per moleculeselected from fluoride, chloride, and bromide, and each alkyl grouphaving from 1 to about 4 carbon atoms; and reactant (c) is an olefin towhich an alkyl radical R' corresponds, wherein R' has the samesignificance as above;such that the mole ratio of reactant (a) toreactant (b) is from about 0.5:1.0 to about 1:1, and the ratio ofreactant (c) to reactant (a) is selected to confer in said productmixture of tetraalkylsilanes, the desired concentration of alkylradicals derived from said olefin.
 2. A process of claim 1, wherein saidreaction temperature is from about 150° C. to about 230° C.
 3. A processof claim 2, wherein said temperature is from about 180° C. to about 230°C.
 4. A process of claim 1, wherein said alkali metal aluminumtetraalkyl has the formula NaAlR'₄, wherein the 4 alkyl radicalsrepresented by R' are the same.
 5. The process of claim 4, wherein saidalkali metal aluminum tetraalkyl is sodium aluminum tetraoctyl.
 6. Aprocess of claim 1, wherein said reactant (b) is methyltrichlorosilane.7. A process of claim 1, wherein said reactant (b) isdimethyldichlorosilane.
 8. A process of claim 1, wherein said reactant(c) is decene-1.
 9. A process of claim 1, wherein said reactant (c) is amixture of octene-1 and decene-1.
 10. A process of claim 1, whereinabout 0.75 mole of reactant (a) is employed for each mole of reactant(b), and per each mole of reactant (b) about 1.5 mole of reactant (c) isemployed, such that the ratio of alkyl radicals in said product mixtureof tetraalkylsilanes, derived from reactant (c) and reactant (a), isabout 2:1.
 11. A process for the preparation of a mixture oftetraalkylsilanes, said process comprising contacting reactants (a),(b), and (c) at a reaction temperature, wherein:reactant (a) is analkali metal aluminum tetraalkyl having the formula MAlR'₄ wherein M isan alkali metal selected from the class consisting of lithium, sodium,and potassium, R' is an alkyl radical having from about 8 to about 14carbon atoms, and the radicals depicted by R' are alike or different;reactant (b) is an alkylhalosilane having two halo groups per moleculeselected from fluoride, chloride, and bromide, and each alkyl grouphaving from 1 to about 4 carbon atoms; and reactant (c) is an olefin towhich an alkyl radical R' corresponds, wherein R' has the samesignificance as above;such that the mole ratio of reactant (a) toreactant (b) is from about 0.5:1.0 to about 1:1, and the ratio ofreactant (c) to reactant (a) is selected to confer in said productmixture of tetraalkylsilanes, the desired concentration of alkylradicals derived from said olefin.
 12. A process of claim 11 whereinsaid reaction temperature is from about 150° C. to about 230° C.
 13. Aprocess of claim 12 wherein said temperature is from about 180° C. toabout 230° C.
 14. A process of claim 11, wherein said alkali metalaluminum tetraalkyl has the formula a NaAlR'₄, wherein the 4 alkylradicals represented by R' are the same.
 15. A process of claim 14,wherein said alkali metal aluminum tetraalkyl is sodium aluminumtetraoctyl.
 16. A process of claim 11, wherein said reactant (b) isdimethyldichlorosilane.
 17. A process of claim 11, wherein said reactant(c) is decene-1.
 18. A process of claim 11, wherein said reactant (c) isa mixture of octene-1 and decene-1.
 19. A process of claim 11 whereinabout 0.75 mole of reactant (a) is employed for each<mole of reactant(b), and per each mole of reactant (b) about 1.5 mole of reactant (c) isemployed, such that the ratio of alkyl radicals in said product mixtureof tetraalkylsilanes, derived from reactant (c) and reactant (a), isabout 2:1.
 20. A process of claim 1, wherein said alkali metal aluminumtetraalkyl is formed in situ.